I got that tip from David Chang and he wasn't specific (re the grit). My guess is

Options

would the grit drop off if you agitated them? Like tossing them (dried) in a salad spinner or a colander? I'd give that a try. Otherwise, just pulverize them in a Cuisinart.

I heard of this trick several years ago from another woman who hated the texture of mushrooms. She loved the flavor, but not the texture. So she pulverized dried mushrooms into a powder and used it on pizzas, pastas, soups, etc.

You can't do anything about the length of your life, but you can do
something about its depth. - M